Understanding Stream Gauges

Little River Tennessee water level

Guides and fly shops routinely spit out numbers from stream gauges, often expecting you to react with pure delight or sheer terror when you hear them. The fact is, unless you spend a lot of time on the water as an angler, paddler or other related water bum, those numbers won’t make a lot of sense to you. Most folks would probably just like to know whether or not they can go fishing. But the better you understand these numbers, the better decision you’ll be able to make on if to go, where to go and what to expect when you get there.

Stream Gauge Basics

There are a lot of things about reading these gauges that are extremely simple while other aspects can get a bit complex. Many things regarding how water flow is going to impact a stream, you just have to see for yourself to truly understand. Then you can relate that to a gauge number and get a pretty good idea of what that water will look like before you leave the house.

Before these gauge readings were posted on the internet, you had to just make your best guess and/or drive to the river to see if it was going to be too high to fish. Even now, with these numbers so easily accessible, there will sometimes be some guesswork, but at least it’s a much more educated guess!

Accessing Stream Gauge Info

Water Flow Data for smartphone
River Data App

The USGS has stations all over the country and there are a number of different search features to locate the gauge on or nearest the fishery in which you’re interested. Many larger rivers will have multiple stations spread out on different parts of the river. You can, of course, use a search engine to locate a specific place. Or go to usgs.gov and begin your search there. There are also a number of apps that can be downloaded. They make searching for a particular location much simpler and keep that information right in your pocket. I use an app called RiverData that gives you access to any river gauge in the country.

Stream Gauge Locations

It’s important to note that not every stream has a gauge. So, you sometimes have to rely on the closest gauge to your fishery and assume that both water systems received similar weather. For example, if I’m going to fish Deep Creek in the Smokies, the nearest gauge is on the Oconaluftee. Most of the time, Deep Creek is going to get the same or similar rain events as the Oconaluftee… but not always.

And even when you have a gauge on the stream you’re specifically interested in, isolated weather systems will sometimes skew the data. For instance, Little River has a gauge located in Townsend, below the confluence of the three prongs. So, if the water rises on any of those prongs, it will ultimately impact the numbers on the gauge downstream in Townsend. Usually if the gauge numbers are reading high in Townsend, the water will be up on all three prongs as they are close enough together that they typically receive similar weather. However, there have been occasions when there was an isolated heavy rain on East Prong that only raised water levels on that branch. Of course, the downstream gauge in Townsend reflected that spike but the West Prong didn’t come up at all.

Unless you’re closely tracking every weather system, there’s just no way to account for something like that. Stream gauges are wonderful tools for determining water levels before you make the trip to the river. But without multiple stream gauges spread out on different sections of every stream in a watershed, you will often, to some extent, be making decisions based on probability rather than 100% certainty.

Understanding Stream Gauge Tools

stream gauge options smoky mountains

Not every gauge provides the same information. Some will provide a cubic feet per second (cfs) reading, some will provide a height reading (usually measured in feet), some will include a temperature reading and many have all three. A handful will get even more in the weeds and provide things like dissolved oxygen readings. For real water flow nerds, most will also allow you view charts in weekly, monthly and annual views. As long as a gauge has been in a location for forty years, I can probably look up what the flow was in that location forty years ago!

It’s also worth mentioning that different gauges may update at different intervals. Most will update at least once an hour while some may provide updates every 15 minutes. But none (that I know of) are providing data feedback in real time. Just above the selected chart will usually indicate the last time the data was updated.

CFS Reading
Smoky Mountains water flow
Stream gauge in CFS

This reading tells you what the flow of the stream is. If the reading is 125cfs, it means that the flow is 125 cubic feet per second. A lot of anglers that really know a stream rely heavily on this number. However, the more casual angler may be easily deceived by this number as the “ideal flow” can vary significantly from stream to stream. The broader and sometimes flatter a streambed is, the more water flow it can comfortably accommodate.

So, 800cfs on a steep, narrow mountain stream may be a total blowout and not fishable at all. On a wider, flatter, low elevation mountain stream, 800cfs might be perfect. On a flat, 75-yard wide tailwater like the Clinch, 800cfs might be considered as a low flow. On a side note, I use generation schedules and data provided by TVA for local tailwater information.

Gauge Height Feet
Little River stream gauge
Stream Gauge in Feet

This reading tells you how high the water is on the gauge and gives you, I think, a little more “universal” reading. At least when it comes to mountain streams, about 2’ on that gauge is nearly always going to be close to “normal flow,” regardless of how wide or steep the stream is. For instance, the Oconaluftee is at a normal, near perfect level when it is at 2’ but may be flowing at around 550cfs. Little River is also normal and near perfect at 2’ but may be flowing at around 200cfs.

Again, there are a lot of variables like stream size and gradient but typically, in most Smoky Mountain streams, 2.5’ is the high side of good. In other words it is still wadeable in most of the usual spots but more difficult. When you reach 3’ on the gauge, you might still find some wadeable spots in isolated areas of small streams but pickings will be really slim. If you don’t know the water really well, don’t mess around with this. Beyond 3’, you’re likely just looking at a blown out river!

Water Temperature
Stream Gauge Water Temperature

You won’t find this feature on every gauge, but some will have it. It’s a nice feature but you have to keep in mind that it’s reading temperature where the gauge is and water temperature will change significantly as you gain elevation on a stream. For example, the Little River gauge is located in Townsend at about 1100’ in elevation. If you’re going to fish Little River around Elkmont Campground, your elevation will be around 2300’. That coupled with more stream canopy, means your water temperature at Elkmont should be considerably cooler than the gauge reading at Townsend.

It’s not an exact science but as a general rule, you drop about 4-degrees water temperature for every 1000’ you gain in elevation. So, if the stream gauge for Little River reads 62-degrees, the water temperature at Elmont should be closer to 58-degrees. This can make an enormous difference when you’re trying to find feeding trout.

Mr. Rapidan Emerger

Mr. Rapidan Emerger
Mr. Rapidan Emerger

The Mr. Rapidan fly pattern was originated by Harry Murray in the 1970’s. Originally tied as a dry fly, it was designed to be a buoyant, visible fly for the choppy waters of Virginia. Does that sound familiar? It should, because much of the trout water in Virginia is very similar to the trout water in Tennessee!

Like many other fly patterns I write about, the Mr. Rapidan has A LOT of branches on its family tree. In fact, if you visit Harry Murray’s online site, you’ll more likely find a description of the Mr. Rapidan family of flies. We’re not going to get into that this time, but you’ll find everything from dry flies to nymphs to ants in the Mr. Rapidan family.

But you’ve surely noticed that the title of this article is not Mr. Rapidan Ant or Mr. Rapidan Family. We are focused on the emerger, mainly because it is time for Quill Gordons to hatch and this is the best pattern for a Quill Gordon emerger I’ve ever used.

The Quill Gordon mayfly is one of the first good hatches of the year in the Smokies. Most folks will tell you it starts coming off around the third or fourth week of March. I wish it was that simple. As an early season hatch, it can be one of the toughest hatches of the year to time right.

Mayflies don’t time their emergence based on a calendar. It usually has more to do with water temperature. When water temperatures get into the 50’s and remain there for the better part of a few days, Quill Gordons will begin to hatch. Usually that’s late March but if we get a warm spell in February, they’ll come off then. If we get a really cold early spring, they may not come off until April. This year, all indications are that they’ll be right on schedule, but it’s still too soon to tell.

During a hatch, some mayfly species spend a fair amount of time on the surface before they fly off. Those are pretty easy picking for trout. However, unless you catch a Quill Gordon hatch on a particularly cool or damp day, they get off the water in a hurry and trout don’t get much of a look at the adults. So the trout often focus their attention more on the emerging insects.

Enter the Mr. Rapidan Emerger. While there are very specific Quill Gordon wet fly patterns, I haven’t found any that outproduce the Mr. Rapidan Emerger. I will sometimes fish it as a dropper below a Quill Gordon dry fly, but most often, I like to fish it by itself or in tandem with another wet fly. Of course, it depends on the specific run but I most often like to fish it on a tight line, “twitching” the rod tip periodically through the drift.

Some variations of this fly have a tail, usually made of pheasant tail fibers. The variation I included does not.

Mr. Rapidan Emerger

Hook: TMC 3769 #14-10
Thread: 8/0 Grey
Rib: Small copper wire
Tail (optional): Pheasant Tail
Body: Dark hare’s ear dubbing
Thorax: Cream antron dubbing
Hackle: Natural hen neck, swept rearward

2021 Covid Policies

Social distancing guidelines will be adhered to on all trips and are pretty easy to follow on the stream. But there will be a few changes to the logistical side of the trip that we will be following from now until further notice.

  • While we may still meet at a convenient location, clients will need to follow in their own vehicle to the stream or trailhead.
  • Please do not be offended that I will not be shaking your hand when we meet.
  • I am always prepared with a mask but don’t usually wear it on the stream as we are able to maintain a safe distance on the stream and we are outdoors. I also do not require you to wear one on the stream. However, if you are more comfortable wearing one, please do. And if you are more comfortable with me wearing one, I gladly will.
  • Clients are encouraged to bring their own rods and wading gear. If needed, you may still use mine at your own risk. I will be cleaning any loaner rods and wading gear before and after each use.
  • I am still happy to provide lunches for full day trips and assure you that the prep and packaging process will strictly follow all necessary guidelines. However, I realize this may make some uncomfortable and you are more than welcome to bring your own food without fear of offending me! Just please let me know with as much notice as possible.
  • I will be practicing social distancing guidelines on the stream and washing my hands throughout the day. I would ask all clients to please do the same.
  • You are encouraged to bring hand sanitizer along to regularly wash hands. I also usually have extra.
  • Health and safety take precedence over service and profit right now. If I do not feel healthy and well, for your safety, I will cancel the trip. I expect all clients to to the same.

The bottom line is we still want to go fishing, right?! But we want to be safe and responsible in the process. If there is anything else I can do to accommodate or make your trip more comfortable, please let me know.

Smokies Fishing Report

abrams creek
meter smokies fishing report

Location

Smoky Mountains

Water Levels

Little River: 585cfs / 2.78 feet
Pigeon: 1180cfs / 2.99 feet
Oconaluftee: 1140cfs / 2.69 feet
Cataloochee: 237cfs / 3.05

Water Temperatures (approximate)

Low elevations: 42 – 45 degrees
Mid elevations: 40 – 44 degrees
High elevations: 34 – 37 degrees

Current Conditions

Streams in the mountains are still running a little on the high side. They have been slowly, steadily dropping the last few days, but today’s rain may have something to say about that. Water temperatures are still well below ideal but they’re what you’d expect for February.

Projected Conditions

The week ahead is looking promising with a nice warm-up expected and we may see some “okay” fishing by the end of the week. Remember that it takes time for those water temperatures to come up and one or two warm afternoons won’t have much impact. We need a string of warmer days and more important, warmer overnights. Those overnight lows will have the biggest impact on water temperature this time of year.

The biggest x-factor right now is the rain that we are getting right now. As long as it doesn’t give water levels too much of a spike, I think you may see some decent days by the weekend.

Tips

In general, you want to seek out slower water and you want to fish the warmest water possible right now. Try to concentrate your efforts on the middle of the day, stick to the lower elevations and look for areas that get a little more sunlight. Fishing high water can be tough and it can be dangerous. Keep an eye on those water levels. It’s not an exact science but typically, I consider around 2.5′ on the gauge to be the high side of good. Ideally, you want it more around 2′. Between 2.5′ and 3′ might give you a little bit of manageable water in very select locations, but you better know what you’re doing. Above 3′ will leave you very little fishable water and is really just unsafe.

Hatches/Fly Suggestions

There is very little in the way of hatches this time of year but you may run into the occasional Blue Wing Olive. Small dark stoneflies and caddis may also make an appearance. Most everything coming off the water will be small, in the #18 – 20 range. I would primarily fish dark colored nymphs deep and slow. A black or olive Zebra Midge would be a good bet. I do well with “peacock flies” in the #14 – 16 range this time of year, like Zug Bugs, Prince Nymphs, etc. In the right water, a larger stonefly nymph may entice a nice brown trout.

Featured Fly

girdle bug
Girdle Bug

Smokies Fishing Report

Date of Report

February 15, 2021

Location

Smoky Mountains

Water Levels

Little River: 777cfs / 3.06 feet
Pigeon: 1660cfs / 3.42 feet
Oconaluftee: 1390cfs / 2.95 feet

Water Temperatures (approximate)

Low elevations: 44 – 47 degrees
Mid elevations: 37 – 40 degrees
High elevations: 32 degrees

Current Conditions

Conditions haven’t changed much since last report and are what you’d likely expect in February. Water temperatures are way below ideal and fishing is very slow. Streams are running high on the Tennessee side of the park from recent rainfall. Use extra caution as some of the bigger streams may be difficult to wade. Most streams on the North Carolina side are a little lower but still running high. Water temperatures are running slightly higher on the North Carolina side as well.

Projected Conditions

It doesn’t look like we’ll see much improvement in the coming week. With air temperatures remaining cold and rain expected almost every day, it’s more likely things are going to get worse!

Tips

In general, you want to seek out slower water and you want to fish the warmest water possible right now. Try to concentrate your efforts on the middle of the day, stick to the lower elevations and look for areas that get a little more sunlight. Remember, water that is too cold makes for slow fishing but water that is too high makes for very dangerous fishing. Unless you know these streams really well, I wouldn’t mess with them at this level. If you do have a lot of experience on these streams, please be very careful!

Hatches/Fly Suggestions

There is very little in the way of hatches this time of year but you may run into the occasional Blue Wing Olive. Small dark stoneflies and caddis may also make an appearance. Most everything coming off the water will be small, in the #18 – 20 range. I would primarily fish dark colored nymphs deep and slow. A black or olive Zebra Midge would be a good bet. I do well with “peacock flies” in the #14 – 16 range this time of year, like Zug Bugs, Prince Nymphs, etc. In the right water, a larger stonefly nymph may entice a nice brown trout.

Featured Fly

Girdle Bug

Smokies Fishing Report

Date of Report

February 8, 2021

Location

Smoky Mountains

Water Levels

Little River: 392cfs / 2.44 feet
Pigeon: 843cfs / 2.62 feet
Oconaluftee: 545cfs / 1.94 feet

Water Temperatures (approximate)

Low elevations: 37 – 40 degrees
Mid elevations: 33 – 36 degrees
High elevations: 32 degrees

Current Conditions

Conditions are what you’d likely expect in February. Water temperatures are way below ideal and fishing is very slow. Streams are running full on the Tennessee side of the park from recent rainfall. Use extra caution as some of the bigger streams may be difficult to wade. Most streams on the North Carolina side are at normal flows and will be easier to navigate. However, water temperatures are a little colder on the NC side as well, so pick your poison!

Projected Conditions

We get a pretty nice warm-up through the week, but as that warm-up melts high elevation snow, don’t expect much in the way of warming water temperatures. That warming trend also comes with what may be significant rainfall, so water levels may come up substantially after Thursday. And another cold front with snow expected over the weekend.

Tips

Other than seeking out slower water, you want to fish the warmest water possible right now. Try to concentrate your efforts on the middle of the day, stick to the lower elevations and look for areas that get a little more sunlight.

Hatches/Fly Suggestions

There is very little in the way of hatches this time of year but you may run into the occasional Blue Wing Olive. Small dark stoneflies and caddis may also make an appearance. Most everything coming off the water will be small, in the #18 – 20 range. I would primarily fish dark colored nymphs deep and slow. A black or olive Zebra Midge would be a good bet. I do well with “peacock flies” in the #14 – 16 range this time of year, like Zug Bugs, Prince Nymphs, etc. In the right water, a larger stonefly nymph may entice a nice brown trout.

Featured Fly

Zug Bug